Computer systems and other electronic systems provide for a large number of stationary, mobile, portable and hand-held devices. These systems generally comprise a user interface with a display and keys. The display may comprise light-emitting elements, such as light-emitting diodes, for displaying information or for illuminating the display. Furthermore, the keys, that may be arranged in a key pad, may comprise light-emitting elements, such as light-emitting diodes, for illuminating the keys or providing information to the user on the keys. As physical dimensions of these devices grow smaller and demands on the displays and keys grow larger, power consumption of these systems in general and the light-emitting devices in particular plays an important role.